Bombs have long been a tool for devotees of the range of fringe American political thought. From anarchists to racists, their methods have wrought havoc -- but also have created backlash.

The bombs allegedly sent by a passionate Trump supporter to prominent liberals are a reminder that American history is littered with violence, with both the left and right pursuing political ends with explosives.

For these radicals — including Albert Parsons, editor of the anarchist publication The Alarm -- dynamite was "a genuine boon for the disinherited." When combined with mass-produced gas or water pipes, dynamite gave desperate men an easily concealed and transported means to disrupt the system they so resented.

The gas pipe bomb in the 1880s was a weapon deployed by revolutionaries against powerful institutions of capital. Activists were willing to die for their beliefs, and used bombs in response to what they saw as everyday or "structural" violence, whereby states, governments and powerful companies pursued their own interests by exploiting ordinary people, and harnessed the instruments of "law and order" to shut down peaceful channels of dissent and change.

Bombs were again used in the famous Wall Street explosions on Sept. 16, 1920. At the financial heart of the country, near the banking giant J.P. Morgan and Co. building, 100 pounds of dynamite hidden in a horse-drawn cart detonated, sending shrapnel into the bodies of passersby and killing 38 people. Hundreds more were injured. It was the biggest terrorist incident in the United States until the Oklahoma City bombing in 1995, and was never solved.

Pipe bombs were again wielded for political purposes in the United States in the polarized 1960s and 1970s. The Weather Underground saw themselves as heirs to the 1880s anarchist revolutionaries and believed violence was necessary to achieve social and political change.

The February 1962 pipe bombs exploded as the Reverend Brooks Walker and the Reverend John Simmons were participating in a discussion panel hosted by a synagogue in Beverly Hills, with the title "Extreme Right -- Threat to Democracy?"

The March 1963 pipe bomb exploded on the same night that the Rev. Brooks Walker was sworn in as President of the Association for the United Nations. The incident prompted Republican Sen. Thomas Kuchel to denounce the work of those he termed the "fright-peddlers" who encouraged such behavior.

No one was killed. But these bomb attacks, like the pipe bombs sent in early October 2018 to Democratic leaders, targeted individuals and their families who were vocal opponents of what they saw as the inflammatory, polarizing words and actions of extremists on the right.

Since the invention of dynamite, bombs have been a tool of choice for devotees of the entire range of fringe American political thought. Anarchists, radical left-wingers and racial supremacists, as politically different from each other as night and day, have been united in one thing: their use of a particular form of violence to achieve political ends.